본 연구에서는 상용되는 금속브라켓의 물리, 화학적 성질을 평가하기 위하 여 치수 정밀도의 측정 및 제조 오차의 분석, agar overlay test를 통한 세 포독성 시험, 성분 분석 및 인공타액 내에서의 성분 용출 시험 그리고 전기 적 부식을 이용한 동전위분극 시험을 시행하였으며 다음과 같은 결과를 얻 었다.
1. 치수 정밀도의 측정에서 angulation의 제조 오차는 각 제품 간의 차이가 없었으나, torque의 제조 오차는 CC에서 유의한 차이를 보였다(P<0.05).
2. Agar overlay test를 통한 세포독성 시험에서는 사용된 모든 제품에서 세포독성을 나타내지 않았다.
3. 성분 용출 시험에서 시간 경과에 따른 금속성분의 용출량은 일정한 양상 을 나타내지 않았으나 최종 누적 용출량은 증가하였다.
4. 금속성분의 최종 누적 용출량에서 KA는 Cr이 유의성 있게 많이 용출되 었고, CC는 Mo과 Ni이 유의성 있게 많이 용출되었으며, 특히 Ni의 과다 용출로 인해 전체 금속성분 용출량도 가장 많았다(P<0.05).
5. 동전위분극 부식 시험에서는 CC에서 Ez와 Ec가 유의성 있게 작은 값을 나타냈으며 이는 부식 저항성이 가장 낮음을 의미하였다(P<0.05).
이상의 결과를 통하여, 금속 브라켓의 여러가지 성질을 확인할 수 있었다.
이를 기반으로 금속 브라켓의 물리, 화학적 및 생물학적 성질에 대한 표준 을 정립하고 상용되는 브라켓의 평가 기준으로 삼아야 한다.
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Abstract
Physical, chemical and biological evalution of commercial metal brackets
(Directed by Professor Chung Ju Hwang)
Joo Hyoung Kim Dept. of Dentistry
The Graduate School, Yonsei University
Recently unverified foreign-made brackets are being imported but there are no standards specified for brackets distributed in the domestic market, and even international standards only specify terminology related to brackets and not their physical properties. Thus, this study aims to evaluate the physical, chemical, and biological properties of various orthodontic metal brackets being distributed in Korea through scientific methods.
Four bracket systems were chosen : Archist(Korea), Victory(USA), Kosaka(Japan), Confidence(China). For the above mentioned metal bracket systems, the following properties were evaluated : "Dimensional accuracy" measures how accurately the brackets match the specifications presented by the manufacturer, "cytotoxicity test" measures how hazardous it is to the human body, "composition analysis" of the brackets, "dissolution test" measures the amount of metal ions released from the metal brackets placed in artificial saliva, "potentiodynamic test"
measures the amount of corrosion of metal brackets using an electrical current.
There was no statistically significant difference in manufacturing error in angulation among the bracket systems, but the manufacturing error in torque for the Confidence system showed a statistically significant difference. No bracket system showed cytotoxicity in the agar overlay test. In the dissolution test, rate of dissolution was not constant, but the total accumulated dissolution amount increased with the elapse of time.
In the final accumulated dissolution, a large amount of Cr was released from Archist brackets, and a large amount of Ni was released from Confidence brackets which also had the highest total amount of metal dissolution. Confidence brackets had the lowest corrosion resistance in the potentiodynamic test.
From the above, we could confirm various properties of metal brackets.
Based on the present study, more specific standards must be established for the physical, chemical, and biological properties of metal brackets and made a testing basis for commercial metal brackets.
Key word : orthodontic bracket, standard, cytotoxicity, dissolution, corrosion